Improving 4AGE Largeport head flow?

[oldeskewltoy]

Based on connecting some simple thoughts.... I believe I've come up with a way to boost largeport 4AG flow. By boosting, I'm talking about stock to medium wild. The simple thoughts being.... a) highest velocity at roof, or back of port, b) smallport head makes more torque - partially because the ports are smaller, BUT partially because the ports have a different shape

smallport


note the splitter is uniform from floor to roof - not rounded "I" shaped like between a womans clevage



What I did was to use the smallport roof design, and modified the largeport splitter








Here is the view from inside the combustion chamber





Opinions????

[hks7mgt]

i don't know if i'm off topic, but i was under the impression dudes ported their small port head out in a special way to achieve the optimal porting/flow for the 4A heads. The bigport was never going to work for the 'best' flow you could achieve. Didn't all the atlantic engines and the like start with the small port heads and do some magic.

either way, i like your thinking, how has it improved on the flow bench?

[oldeskewltoy]

i don't know if i'm off topic, but i was under the impression dudes ported their small port head out in a special way to achieve the optimal porting/flow for the 4A heads. The bigport was never going to work for the 'best' flow you could achieve. Didn't all the atlantic engines and the like start with the small port heads and do some magic.

either way, i like your thinking, how has it improved on the flow bench?

The F/A shop near me - Loynings Engine Service - used largeport heads, at least as far as I know. I've never seen an Atlantic head begin as a smallport.

I'm contemplating cleaning the porting up a bit and then bringing it to Loynings... I just have to decide to spend $75 to get it tested on the flow bench.

[oldcorollas]

ask yourself... WWLD

fwiw, the difference there is also about development of casting technology.

[dangdang]

Good work, this is a subject that greatly interests me.

Personally I would always start with a smallport for both n/a and forced, so much better cylinder filling with them. First time I drove a bigport with the tvis removed was just sad for low response. A major reason I went smallport on my gte, just didnt want hassles of tvis or its removal and then a horribly unresponsive low comp engine off boost.

My experience of port sizes comes from playing with Ford small block v8's namely clevelands, the 4v is just overkill, even for a oval track high rpm engine they are just WAY to big. Hence most aftermarket manufacturers offer a "3v" casting now, something between the factory 2v and 4v. I will be porting a small port head soon for an n/a build of mine coming up.

As far as this head goes what sort of setup will it be run with? Tvis, no Tvis, carb, injected, cams, valves etc

What you've done there looks to be great for airspeed just dont take anything out of the short side radius imo.

I also believe having looked at a bigport head I have in the shed that unshrouding the valves would help greatly.

Also don't polish it too far as barrier de lamination has now been found to be better for flow of ports than a shiny smooth surface.

Just my 2c Hope it flows as well as you hope.

[oldeskewltoy]

What you've done there looks to be great for airspeed just dont take anything out of the short side radius imo.

I also believe having looked at a bigport head I have in the shed that unshrouding the valves would help greatly.

Also don't polish it too far as barrier de lamination has now been found to be better for flow of ports than a shiny smooth surface.

Just my 2c Hope it flows as well as you hope.

I try to avoid touching the port floors... unless if there is a large casting blob.

From the local F/A shop... deshrouding for flow.... not as substantial as you might think.... BUT removing said "shrouds" to remove potential ignition points for pre-ignition, THAT can be substantial.

Here are two heads I've done chamber work in... the top photo was removing the barest minimum without enlarging the chambers excessively... 36.25cc to 37cc

http://i79.photobucket.com/albums/j1...velesshead.jpg


This next photo shows a MASSIVE amount of enlargement 36.25cc to 39.25cc. This head is being used to detune a high comp bottom end (nearly 12 to 1) to function on stock electronics and mild cams(256 type)

http://i79.photobucket.com/albums/j1...reandafter.jpg



I do my best to leave a less then polished bowl/port on the intake side - http://i79.photobucket.com/albums/j1.../in22panel.jpg

but on the exhaust I usually polish them up to minimize carbon adhering to the port walls - http://i79.photobucket.com/albums/j1...reandafter.jpg

[abently]

Getting flow numbers is one thing, but in this day and age its all about velocity and what speeds at different points in the port.

Unless you have the time and equipment OR flow software and access to a CNC, I just leave it for the (rare as hen's teeth) pro's to do it.

[dangdang]

Getting flow numbers is one thing, but in this day and age its all about velocity and what speeds at different points in the port.

Unless you have the time and equipment OR flow software and access to a CNC, I just leave it for the (rare as hen's teeth) pro's to do it.

No fun in that! and some of us have heads to spare to play as is our pleasure

Rare as hens teeth pros cost rare as hens teeth dollars, I know my pockets are not that deep. Luckily I know one and he is happy to port just one inlet, chamber and exhaust for me so as I can copy and learn on the others...ace!

I don't have access to software but neither do some of the top engine builders I know of, a flow bench at least perhaps for some tangible evidence of an improvement.

I reckon good on you Oldskewltoy, if some of us don't experiment, try and learn this sort of thing it becomes a lost practice relegated to the memories of old men..fuck that!

[trdee]

Getting flow numbers is one thing, but in this day and age its all about velocity and what speeds at different points in the port.

Unless you have the time and equipment OR flow software and access to a CNC, I just leave it for the (rare as hen's teeth) pro's to do it.

it's not all about velocity. you can have super mega fast velocity by turning your ports into pinholes. something tells me that wont make you much power though

You are right, it is a complex science, but it's not black magic. Half the pros out there have nfi what they're doing anyway lol

[oldeskewltoy]

Half the pros out there have nfi what they're doing anyway lol

I try to follow one over riding rule when I do porting - First, and foremost, do no harm!

[amichie]

One place on the low side of the port that usually needs attention is the short side radius. Toyota seem to leave deep machining marks below the valve seat on many heads I have seen.

[abently]

it's not all about velocity. you can have super mega fast velocity by turning your ports into pinholes. something tells me that wont make you much power though

You are right, it is a complex science, but it's not black magic. Half the pros out there have nfi what they're doing anyway lol

When I talk about professionals, I mean professionals who's main source of work and income comes from the racing scene, therefore the end result (and $$$) must show tangible benefits otherwise you quickly become old news and retire to the mainstream consumer pool.

if some of us don't experiment, try and learn this sort of thing it becomes a lost practice relegated to the memories of old men..fuck that!

No it won't, because it is a science now more than ever and Engineers around the world are been taught how to design, test (simulate) and re-design complete engines, which means the days of flow bench work is marked for closure in the next decade.

[dangdang]

Point taken, but what engineer is going to test and re-design my complete 4age engine this year and not in ten?

Definitely new engines are incomparably better than those designed 20+ years ago, even the porting of say the 4age is all about complimenting the design that Toyota spent millions of dollars doing in the first place, not radically altering it.

To radically alter I agree requires the help of CAD, flow software and probably to pull it off best an after market casting.

What you are saying abently, makes sense for new vehicles and commercially viable after market heads such as those made for American V-8's for example but doesnt translate to what oldskewl is doing here, "Improving 4AGE Largeport head flow" well at least having a crack at improving for "about stock to medium wild" and I'm sure for no other value than just personal satisfaction.

So which scientist/engineer is going to port my 4age head for me? Now or even in ten years.

And who makes an off the shelf ported 4age head or an after market casting for that matter??

[oldeskewltoy]

what oldskewl is doing here, "Improving 4AGE Largeport head flow" well at least having a crack at improving for "about stock to medium wild" and I'm sure for no other value than just personal satisfaction.

actually I am trying to make a few $$ - http://forums.club4ag.com/zerothread?id=82022

[dangdang]

Ahh well I take it all back then!

No I've connected the dots and I do remember having seen your thread over at club4ag.

Still doesn't change my opinion of hand ported heads.

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